/*
 * The contents of this web application are subject to the Mozilla Public License Version 
 * 1.1 (the "License"); you may not use this web application except in compliance with 
 * the License. You may obtain a copy of the License at http://www.mozilla.org/MPL/.
 * 
 * Software distributed under the License is distributed on an "AS IS" basis, 
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 
 * for the specific language governing rights and limitations under the License.
 * 
 * The Original Code is owned by and the Initial Developer of the Original Code is 
 * Composite A/S (Danish business reg.no. 21744409). All Rights Reserved
 * 
 * Section 11 of the License is EXPRESSLY amended to include a provision stating 
 * that any dispute, including but not limited to disputes related to the enforcement 
 * of the License, to which Composite A/S as owner of the Original Code, as Initial 
 * Developer or in any other role, becomes a part to shall be governed by Danish law 
 * and be initiated before the Copenhagen City Court ("K�benhavns Byret")            
 */

using System;
using System.IO;
using System.Text;

namespace Composite.Search.MicrosoftSearchServer
{
    internal abstract class Utf8StringTransformationStream : Stream
    {
        private readonly Stream _innerStream;
        private MemoryStream _ms = new MemoryStream();

        public Utf8StringTransformationStream(Stream innerOuputStream)
        {
            _innerStream = innerOuputStream;
        }

        public override bool CanRead
        {
            get { return false; }
        }

        public override bool CanSeek
        {
            get { return false; }
        }

        public override bool CanWrite
        {
            get { return true; }
        }

        public override void Flush()
        {
            // DO NOTHING HERE
        }

        public override long Length
        {
            get { throw new NotImplementedException(); }
        }

        public override long Position
        {
            get { throw new NotImplementedException(); }
            set { throw new NotImplementedException(); }
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            throw new NotImplementedException();
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotImplementedException();
        }

        public override void SetLength(long value)
        {
            throw new NotImplementedException();
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            if (!_ms.CanWrite)
            {
                // Reopening stream if it was empty
                _ms = new MemoryStream();
            }
            _ms.Write(buffer, offset, count);
        }

        public override void Close()
        {
            // Checking if the stream was already closed
            if (!_ms.CanSeek)
            {
                return;
            }

            _ms.Seek(0, SeekOrigin.Begin);

            var bytes = _ms.ToArray();

            string str = Encoding.UTF8.GetString(bytes);

            string newValue = Process(str);

            if (newValue != str)
            {
                bytes = Encoding.UTF8.GetBytes(newValue);
            }

            _innerStream.Write(bytes, 0, bytes.Length);

            _innerStream.Close();
            _ms.Close();
        }

        public abstract string Process(string str);
    }
}